1. Field of the Invention
The present invention relates to the field of controlled flow, exhaust manifold systems and, more particularly, to apparatus for controlling the flow of missile exhaust gases by preventing recirculation back into the cell of the fired missile from a common exhaust gas manifold or plenum tube connected thereto.
2. Description of the Related Art
In certain military applications, particularly on warships having missile firing capability, the missiles are stored in a series of vertically oriented chambers or cells closely adjacent one another. Exhaust gas outlets are normally provided to duct rocket exhaust gases generated during intended or accidental rocket ignitions to a safe location. In such installations, manifolding of a number of chambers into a common exhaust duct or plenum tube has become conventional.
There have been a number of approaches to the problems attendant upon the use of a common exhaust duct with a plurality of missile storage chambers. It is important to be able to block the exhaust gases from a missile which is being fired from blowing out through the individual chambers of other missiles. This is commonly accomplished by the use of doors or hinged panels which can open into the plenum chamber from the force of an impinging missile exhaust for the chamber containing the missile being fired and which can close off the passage at the base of a missile chamber opening into the exhaust plenum for other missiles.
Eastman U.S. Pat. No. 2,445,423 discloses apparatus having a plurality of individual missile chambers coupled to a common plenum chamber with a plurality of hinged, spring-loaded doors at the juncture of each individual missile chamber with the plenum tube. These doors open for a rocket that is being fired and serve to confine the exhaust gases within the plenum chamber and away from other missile-storage chambers.
There is also the problem of a portion of the rocket exhaust backing up into the chamber of the missile being fired and possibly over-pressurizing or over-heating that missile chamber.
My own prior U.S. Pat. No. 4,044,648, the entire disclosure of which is incorporated by reference as though fully set forth herein, discloses a pair of hinged doors at the base of each missile storage chamber in the passage connecting the chamber to an associated exhaust plenum duct. The pressure forces on opposite sides of the doors during the firing of a missile are balanced to control the degree to which the doors are opened in order to adjust the opening to the varying dimension of the rocket exhaust stream as the missile rises and leaves the chamber upon firing. As a consequence, the rocket exhaust stream functions as a suitable "gas plug" in the opening in order to prevent recirculation of the exhaust gases back into the chamber undergoing firing.
It is important to control the rocket exhaust gas stream so that the gas plug is effective to prevent recirculation of exhaust gases back into the chamber. Control of the rocket exhaust stream on a dynamic basis to develop the gas plug effect appears to be more effective for the intended purpose than the use of fixed structure such as baffles, valves, diverters or the like which oftentimes have the undesirable result of interfering with the direct exhaust gas stream in their attempt to control flow, limit reverse circulation, etc. My prior U.S. Pat. No. 4,683,798, the entire disclosure of which is incorporated by reference as though fully set forth herein, discloses hinged doors near the lower end of each missile storage chamber but spaced from the juncture with the common plenum chamber by a transition region which provides a smooth transition from a generally square cross-section chamber in which a missile is stored and launched to a round exit opening in the chamber which connects with the exhaust plenum. This enhances the gas plug effect and uses it to prevent recirculation of exhaust gases back into the chamber of the missile being fired.
My prior U.S. Pat. No. 4,686,884, the entire disclosure of which is incorporated by reference as though fully set forth herein, discloses an arrangement including sets of doors to close off missile storage chambers coupled to a common plenum chamber upon the firing of a missile in another chamber with the addition of pivotable deflector panels which are installed in transition sections between the missile storage and launch chambers proper and the common plenum chamber.
My following listed prior patents deal with related aspects of rocket exhaust plenum chambers coupled to a plurality of missile launch canisters and the principles of using rocket exhaust gas flow to close the aft doors of missile canisters not presently undergoing launch firing or maintaining such doors closed during the firing of a missile in another canister: U.S. Pat. Nos. 4,134,327, 4,173,919, 4,186,647, 4,324,167, and 4,373,420.
Other patents which may bear a more or less remote resemblance to presently used missile launcher canister closures are the Sherts U.S. Pat. No. 2,679,467 and the Wilson et al U.S. Pat. No. 4,498,261. Both of these patents disclosure pressure blowout safety closures comprising rupturable membranes or panels which are scored to develop predetermined failure lines. Clam-shell shaped closures are disclosed in U.S. Pat. No. 1,130,609 of S. T. Jones and U.S. Pat. No. 2,956,582 of L. A. Pranter. U.S. Pat. No. 2,427,980 of Stinson et al discloses an accordion pleated sidewall for a volume defined by an opening aircraft control surface, such as a flap, so as to provide an automatic assist to the movement of the control surface by trapping air in the volume established by the opening flap. None of these patents relate to the novel aspects of my disclosed invention, as claimed.
Present missile launcher canister aft closures are designed to open along the diagonals of a rectilinear configuration under the influence of the rocket exhaust impingement which causes the aft closure to rupture. The aft closure has previously been scored so that, for example, four triangular petals are formed from the bursting of the aft closure. The petals are bent back by the missile exhaust toward the sill plate and may rest against the sill plate. The resulting opening allows the rocket exhaust to flow into the associated plenum chamber with a corresponding plenum pressure increase. However when the exhaust plume diameter is not sufficient to completely fill the cover opening, the area along the separation diagonals between the triangular petals, in the vicinity of the corners of the rectilinear configuration, allows the now-pressurized plenum gases to recirculate back into the canister. This recirculation can cause undesirable heat transfer and contamination to the missile and/or the canister.
After the missile flies out of the canister, exhaust gases begin to flow from the plenum into the empty canister. This gas flow causes pressure waves and shock waves to be propagated in the air inside the canister. The flow of gases also causes the petals of the aft closure to move to the closed position where they are supported by a petal support grid. It is during the launch interval, however, when the petals of the aft closure are opened without the "plug" of missile exhaust being sufficient to fill the aft opening that the need to close off the outer areas of the opening formed in the corners of the ruptured aft closure develops.